Friday Present a plant stressor, what is known about it, and why it might affect plant 2˚ compounds in an ~ 10 minute presentation. Alternative: present another good plant/stressor response to study and why we should choose it over the ones already chosen.

John Austin: Tom Nawrocki: Maria Chinikaylo: effect of atrazine herbicide on glutathione in corn Jared Nicholoff: David Pupaza: Fungal attack Cassia Cole: Kyle Schimmel: Christina Gambino: predation on caffeine coffee plant Nathan Seabridge: sulfur deprivation on onions Andrew Hasuga: ozone Kenneth Werkheiser: Agrobacterium tumefaciens Kelvin Mejia: High soil salinity Alexis Morgan: Sulfur deprivation on garlic Matt Yatison: UV radiation Michael Yucha: Cold Stress Catherin Morocho: Atrazine? Cold? Shaking?Nutrient deprivation? Bacteria? Nematodes? Ozone? Smog? Heavy metals? Predation? Heat?

Natural Products >100,000 types; 3 main groups >30,000 terpenoids: made from isoprene units >12,000 Alkaloids: derived from amino acids: contain N >8,000 phenolics: contain phenol ring

Other natural products ~ 100 cyanogenic glycosides Release cyanide when plant is damaged Found in seeds of apricots, cherries, other fruits Laetrile

Other natural products > 100 glucosinolates: contain S and N Mainly found in Brassicaceae (crucifers) Made from modified amino acids bonded to glucose Function in defense

Other natural products The genus Allium produces sulfoxides derived from cysteine When plants are damaged they are converted to pungent volatiles

Seeds Seeds are unique feature of plants Plant dispersal units Must survive unfavorable conditions until they reach suitable place (and time) to start next generation Are dormant; dehydration is key Germinate when conditions are right

Seed Development Maturation: cell division ± ceases, but cells still expand Activate new genes for making storage compounds Storage compounds are key for seedlings and crops Proteins, lipids & carbohydrates but vary widely Many 2˚ metabolites

Seed Development Next prepare for desiccation as ABA made by embryo (+endosperm) increases Make proteins & other molecules (eg trehalose) that help tolerate desiccation Next dehydrate (to 5% moisture content) and go dormant

Seed Development Coat-imposed dormancy (maternal effect) Preventing water uptake. Mechanical constraint Interference with gas exchange Retaining inhibitors (ABA) Inhibitor production (ABA) Embryo dormancy (Zygotic effect)

Seed germination Seeds remain dormant until sense appropriate conditions: Water Temperature: some seeds require vernalization = prolonged cold spell Many require light: says photosynthesis is possible often small seeds with few reserves

Seed germination Seeds remain dormant until sense appropriate conditions: Many require light: says that they will soon be able to photosynthesize: often small seeds with few reserves Hormones can also trigger (or stop) germination ABA blocks it GA stimulates it

Seed germination Seeds remain dormant until sense appropriate conditions: Many require light: says that they will soon be able to photosynthesize: often small seeds with few reserves Hormones can also trigger (or stop) germination ABA blocks it GA stimulates it Germination is a two step process Imbibition

Seed germination Germination is a two step process Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it.

Seed germination Germination is a two step process Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it. Seeds with endosperm pop testa first, then endosperm

Seed germination Germination is a two step process Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it. Seeds with endosperm pop testa first, then endosperm Separate processes: can pop testa but not endosperm

Seed germination Germination is a two step process Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it. Seeds with endosperm pop testa first, then endosperm Separate processes: can pop testa but not endosperm Testa and endosperm have different genotypes!

Seed germination Germination is a two step process Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it. Seeds with endosperm pop testa first, then endosperm Next embryo must start metabolism and cell elongation

Seed germination Germination is a two step process Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it. Next embryo must start metabolism and cell elongation This part is sensitive to the environment, esp T & pO2

Seed germination Germination is a two step process Next embryo must start metabolism and cell elongation This part is sensitive to the environment, esp T & pO2 Hormones also play a complex role

Seed germination Germination is a two step process Next embryo must start metabolism and cell elongation This part is sensitive to the environment, esp T & pO2 Hormones also play a complex role GA, Ethylene and BR all stimulate

Seed germination Germination is a two step process Next embryo must start metabolism and cell elongation This part is sensitive to the environment, esp T & pO2 Hormones also play a complex role GA, Ethylene and BR all stimulate ABA blocks

Seed germination Germination is a two step process Next embryo must start metabolism and cell elongation This part is sensitive to the environment, esp T & pO2 Once radicle has emerged, vegetative growth begins

Vegetative growth Once radicle has emerged, vegetative growth begins Juvenile plants in light undergo photomorphogenesis

Vegetative growth Once radicle has emerged, vegetative growth begins Juvenile plants in light undergo photomorphogenesis Juvenile plants in dark undergo skotomorphogenesis Seek light: elongate hypocotyl, don’t unfold cotyledons

Vegetative growth Once radicle has emerged, vegetative growth begins Juvenile plants in light undergo photomorphogenesis Expand cotyledons, start making leaves & photosynthetic apparatus

Vegetative growth Once radicle has emerged, vegetative growth begins Juvenile plants in light undergo photomorphogenesis Expand cotyledons, start making leaves & photosynthetic apparatus Initially live off reserves, but soon do net photosynthesis

Vegetative growth Once radicle has emerged, vegetative growth begins Initially live off reserves, but soon do net photosynthesis Add new leaves @ SAM in response to auxin gradients Add new branches from axillary buds lower down stem if apical dominance wanes

Vegetative growth Once radicle has emerged, vegetative growth begins Add new leaves @ SAM in response to auxin gradients Add new branches from axillary buds lower down stem if apical dominance wanes Roots grow down seeking water & nutrients

Vegetative growth Once radicle has emerged, vegetative growth begins Add new leaves @ SAM in response to auxin gradients Roots grow down seeking water & nutrients 1˚ (taproot) anchors plant 2˚ roots absorb nutrients

Vegetative growth Once radicle has emerged, vegetative growth begins Add new leaves @ SAM in response to auxin gradients Roots grow down seeking water & nutrients 1˚ (taproot) anchors plant 2˚ roots absorb nutrients Continue to add cells by divisions @ RAM

Vegetative growth Roots grow down seeking water & nutrients Continue to add cells by divisions @ RAM Form lateral roots in maturation zone in response to nutrients & auxin/cytokinin

reproductive phase Eventually switch to reproductive phase & start flowering Are now adults!

reproductive phase Eventually switch to reproductive phase & start flowering Are now adults! Triggered by FT protein: moves from leaves to shoot apex in phloem to induce flowering!

Transition to Flowering Adults are competent to flower, but need correct signals Very complex process! Can be affected by: Daylength T (esp Cold) Water stress Nutrition Hormones Age

reproductive phase Are now adults! Very complex process! Time needed varies from days to years

reproductive phase Eventually switch to reproductive phase & start flowering Are now adults! Time needed varies from days to years. Shoot apical meristem now starts making new organ: flowers, with many new structures & cell types

Senescence Shoot apical meristem now starts making new organ: flowers, with many new structures & cell types Eventually petals, etc senesce = genetically programmed cell death: controlled by specific genes

Senescence Eventually petals, etc senesce = genetically programmed cell death: controlled by specific genes Also seen in many other cases: deciduous leaves in fall, annual plants, older trees

Senescence Induce specific senescence-associated genes ; eg DNAses, proteases, lipases Also seen during xylem formation: when cell wall is complete cell kills itself

Senescence Also seen during xylem formation: when cell wall is complete cell kills itself Also seen as wound response: hypersensitive response Cells surrounding the wound kill themselves

Senescence Also seen during xylem formation: when cell wall is complete cell kills itself Also seen as wound response: hypersensitive response Cells surrounding the wound kill themselves Some mutants do this w/o wound -> is controlled by genes!

Light regulation of Plant Development Plants use light as food and information Use information to control development

Light regulation of Plant Development Plants use light as food and information Use information to control development germination

Light regulation of Plant Development Plants use light as food and information Use information to control development Germination Photomorphogenesis vs skotomorphogenesis

Light regulation of Plant Development Plants use light as food and information Use information to control development Germination Photomorphogenesis vs skotomorphogenesis Sun/shade & shade avoidance

Light regulation of Plant Development Germination Morphogenesis Sun/shade & shade avoidance Flowering

Light regulation of Plant Development Germination Morphogenesis Sun/shade & shade avoidance Flowering Senescence

Light regulation of growth Plants sense Light quantity

Light regulation of growth Plants sense Light quantity Light quality (colors)

Light regulation of growth Plants sense Light quantity Light quality (colors) Light duration

Light regulation of growth Plants sense Light quantity Light quality (colors) Light duration Direction it comes from

Light regulation of growth Plants sense Light quantity Light quality (colors) Light duration Direction it comes from Have photoreceptors that sense specific wavelengths

Light regulation of growth Early work: Darwin showed that phototropism is controlled by blue light

Light regulation of Plant Development Early work: Darwins : phototropism is controlled by blue light Duration = photoperiodism (Garner and Allard,1920) Maryland Mammoth tobacco flowers in the S but not in N

Light regulation of Plant Development Early work: Darwins : phototropism is controlled by blue light Duration = photoperiodism (Garner and Allard,1920) Maryland Mammoth tobacco flowers in the S but not in N = short-day plant (SDP)

Light regulation of Plant Development Duration = photoperiodism (Garner and Allard,1920) Maryland Mammoth tobacco flowers in the S but not in N = short-day plant (SDP) Measures night! 30" flashes during night stop flowers

Light regulation of growth Duration = photoperiodism (Garner and Allard,1920) Maryland Mammoth tobacco flowers in the S but not in N = short-day plant (SDP) Measures night! 30" flashes during night stop flowers LDP plants such as Arabidopsis need long days to flower

Light regulation of growth Duration = photoperiodism (Garner and Allard,1920) Maryland Mammoth tobacco flowers in the S but not in N = short-day plant (SDP) Measures night! 30" flashes during night stop flowers LDP plants such as Arabidopsis need long days to flower SDP flower in fall, LDP flower in spring, neutral flower when ready

Light regulation of growth Measures night! 30" flashes during night stop flowers LDP plants such as Arabidopsis need long days to flower SDP flower in fall, LDP flower in spring, neutral flower when ready Next : color matters! Red light works best for flowering

Light regulation of growth Next : color matters! Red light (666 nm)works best for flowering & for germination of many seeds!

Phytochrome Next : color matters! Red light (666 nm)works best for flowering & for germination of many seeds! But, Darwin showed blue works best for phototropism!

Phytochrome Next : color matters! Red light (666 nm)works best for flowering & for germination of many seeds! But, Darwin showed blue works best for phototropism! Different photoreceptor!

Phytochrome But, Darwin showed blue works best for phototropism! Different photoreceptor! Red light (666 nm) promotes germination Far red light (>700 nm) blocks germination

Phytochrome But, Darwin showed blue works best for phototropism! Different photoreceptor! Red light (666 nm) promotes germination Far red light (>700 nm) blocks germination